tipc: use RCU to protect media_ptr pointer
Now the media_ptr pointer is protected with tipc_net_lock write lock
on write side; tipc_net_lock read lock is used to read side. As the
part of effort of eliminating tipc_net_lock, we decide to adjust the
locking policy of media_ptr pointer protection: on write side, RTNL
lock is use while on read side RCU read lock is applied.
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Tested-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index e0625e9..c24a351 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -458,7 +458,7 @@
return -ENODEV;
/* Associate TIPC bearer with Ethernet bearer */
- b->media_ptr = dev;
+ rcu_assign_pointer(b->media_ptr, dev);
memset(b->bcast_addr.value, 0, sizeof(b->bcast_addr.value));
memcpy(b->bcast_addr.value, dev->broadcast, b->media->hwaddr_len);
b->bcast_addr.media_id = b->media->type_id;
@@ -477,7 +477,10 @@
*/
void tipc_disable_l2_media(struct tipc_bearer *b)
{
- struct net_device *dev = (struct net_device *)b->media_ptr;
+ struct net_device *dev;
+
+ dev = (struct net_device *)rtnl_dereference(b->media_ptr);
+ RCU_INIT_POINTER(b->media_ptr, NULL);
RCU_INIT_POINTER(dev->tipc_ptr, NULL);
dev_put(dev);
}
@@ -492,8 +495,12 @@
struct tipc_media_addr *dest)
{
struct sk_buff *clone;
+ struct net_device *dev;
int delta;
- struct net_device *dev = (struct net_device *)b->media_ptr;
+
+ dev = (struct net_device *)rcu_dereference_rtnl(b->media_ptr);
+ if (!dev)
+ return 0;
clone = skb_clone(buf, GFP_ATOMIC);
if (!clone)
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index 2fa86bd..a983b30 100644
--- a/net/tipc/bearer.h
+++ b/net/tipc/bearer.h
@@ -128,7 +128,7 @@
* care of initializing all other fields.
*/
struct tipc_bearer {
- void *media_ptr; /* initalized by media */
+ void __rcu *media_ptr; /* initalized by media */
u32 mtu; /* initalized by media */
struct tipc_media_addr addr; /* initalized by media */
char name[TIPC_MAX_BEARER_NAME];